Jonah is one of the Bible’s lesser known prophets and his book is one of the shortest. The Great Work of Jonah concerns the Kabbalah but also certain aspects of spiritual alchemy as a process of inner transformation. This work offers a new translation of the biblical book of Jonah, remaining very faithful to the Hebrew text. The commentary focuses on the richness of the Hebrew roots and the numerical values of the words. Readers will therefore be able to familiarise themselves with the numerical and semantic techniques for decoding biblical texts, used by the masters of the Talmud and Kabbalists. Through this commentary, the author unveils the potential connections between the Kabbalah and spiritual alchemy.